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Author Topic: Secure rip produces different files for same rip & drive  (Read 1859 times)

JONCAT

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Secure rip produces different files for same rip & drive
« on: August 03, 2008, 11:43:40 pm »

I did some testing over the weekend. Not really done yet as I appear to have a can of worms.

I found some anomalies when ripping. I used JRiver, EAC, 4 drives, and 6 rips. I found pitch variance in a sample from the ripped wav; filesize were the same down to the byte.

Details here:

http://digitanalogue.blogspot.com/2008/08/do-drive-brands-matter-when-ripping.html

any thoughts?
thanks
DC
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Alex B

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Re: Secure rip produces different files for same rip & drive
« Reply #1 on: August 04, 2008, 10:59:38 am »

I did some testing over the weekend. Not really done yet as I appear to have a can of worms.

I found some anomalies when ripping. I used JRiver, EAC, 4 drives, and 6 rips. I found pitch variance in a sample from the ripped wav; filesize were the same down to the byte.

Details here:

http://digitanalogue.blogspot.com/2008/08/do-drive-brands-matter-when-ri...

any thoughts?
thanks
DC

Only one:  ?

Please rephrase your question and fix the link.
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JONCAT

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Re: Secure rip produces different files for same rip & drive
« Reply #2 on: August 04, 2008, 11:41:18 am »

Sorry, link got chopped.

dc
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Alex B

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Re: Secure rip produces different files for same rip & drive
« Reply #3 on: August 04, 2008, 11:46:57 am »

I don't know how Wavelab measures the average pitch. Possibly a difference in the drives' read offset or a read error can make it to detect a different pitch.

A drive cannot change the ripped audio file's "pitch" anyhow. The raw output from an audio CD is binary code - zeros and ones. The contents of the PCM audio stream are calculated later. If the drive cannot momentarily read data correctly for a reason or another then the output is momentarily scrambled - totally wrong. It is not posssible that the output would be only slightly changed.

Do you actually have a problem or do you just have too much spare time? :)
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JONCAT

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Re: Secure rip produces different files for same rip & drive
« Reply #4 on: August 04, 2008, 11:52:09 am »

Look, I'm not freaking out, (man...the left channel sounded 70hz lower for the last 500 milliseconds!!!!), but it is an interesting experiment and warrants further investigation.

I think it's extremely interesting, as I said in the post, that the same two alternate values get reported for the pitch value from 305-1000ms.

If something is affecting the rip adversely, I would never have guessed it to be so repeatable. At least so far....

Wouldn't this have some impact on the Accurate Rip project?

DC

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Alex B

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Re: Secure rip produces different files for same rip & drive
« Reply #5 on: August 04, 2008, 12:18:32 pm »

Edit to my last reply:
As I am not a drive engineer I am not sure if the output would be exactly "scrambled" when a read error occurs. It may also be averaged. However, I don't think it could possibly be anything that would change the perceivable audio quality over a longer period of time.


BTW, did you correct the read offset variences before checking the files?

According to the accurate rip database the drives have the following read offset values:
LITE-ON - DVDRW SOHW-1653S   +12
LG Electronics - BDDVDRW GGC-H20   +667
PLEXTOR - DVDR PX-716AL   +30

Though, these are samples -- 44100 samples in one second so they should not be able to cause a difference over a 500 ms time period. Also the Lite-On and Plextor drives are very close to each other and you said the Lite-On drive produced different results.
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